Poland was in mourning last night after the ­president, his wife and several key government figures were killed in a plane crash.

Their plane hit trees as it tried to land in thick fog at Smolensk, Western Russia, and burst into flames, killing all 97 on board yesterday morning.

President Lech Kaczynski, 60, a one-time ally of Solidarity hero Lech Walesa, and other senior figures ­including Poland’s army chief, central bank governor, MPs and military heads were among the victims.

Polish Prime Minister Donald Tusk described it as the “most tragic event in the country’s post-war history” before travelling to the crash site to pay his respects.

As the Polish ­government called for a week of ­national mourning, people gathered outside the presidential palace in Warsaw to light candles and lay ­flowers.

A two-minute silence to remember those who died will be held today. Poles in London have been ­laying flowers and signing a book of condolence at the Polish Information Centre in Hammersmith.

The Queen and Gordon Brown have sent messages.

Among those killed was the ­president’s personal chaplain Rev Canon ­Bronislaw Gostomski, priest at a Polish church in West London.

Colleague Father Marek Reczek said he was a popular figure at St Andrew’s Bobola Polish Church in Shepherd’s Bush, where he had served for seven years. Parishioner Monika Helsner, 34, said: ­“Everyone is in shock. No one can replace him.”

The presidential plane was a 20-year-old Tupolev TU-154s. There have been 66 crashes ­involving TU-154s – six in the last five years. Last night pilot error was being blamed for the ­tragedy.